U.S. patent number 7,309,388 [Application Number 10/775,979] was granted by the patent office on 2007-12-18 for jet ink composition for low surface energy substrates.
This patent grant is currently assigned to Videojet Technologies Inc.. Invention is credited to Godwin Deng, Arsenia C. Morelos, Linfang Zhu.
United States Patent |
7,309,388 |
Zhu , et al. |
December 18, 2007 |
**Please see images for:
( Certificate of Correction ) ** |
Jet ink composition for low surface energy substrates
Abstract
Disclosed are jet ink compositions suitable for printing on
substrates such as plastics and oil contaminated metals messages
having excellent adhesion, for example, scratch resistance. The jet
ink composition comprises one or more organic solvents, a rosin
resin, and a colorant, and optionally a co-binder resin, e.g., a
vinyl resin. Preferably, the jet ink composition is free or
substantially free of a cellulose nitrate resin and/or a slow
evaporating solvent. The present invention further provides a
method for printing scratch resistant messages on a low surface
energy substrate comprising projecting a stream of droplets of the
jet ink composition to the substrate, controlling the direction of
the stream so that the droplets are caused to form the desired
printed messages, and allowing the messages to dry.
Inventors: |
Zhu; Linfang (Naperville,
IL), Deng; Godwin (Schaumburg, IL), Morelos; Arsenia
C. (Glendale Heights, IL) |
Assignee: |
Videojet Technologies Inc.
(Wood Dale, IL)
|
Family
ID: |
32830002 |
Appl.
No.: |
10/775,979 |
Filed: |
February 10, 2004 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20040154495 A1 |
Aug 12, 2004 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
60446543 |
Feb 12, 2003 |
|
|
|
|
Current U.S.
Class: |
106/31.4;
106/31.72; 106/31.75 |
Current CPC
Class: |
C09D
11/36 (20130101) |
Current International
Class: |
C09D
11/02 (20060101) |
Field of
Search: |
;106/31.4,31.75,31.72 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2105735 |
|
Mar 1983 |
|
GB |
|
60092370 |
|
May 1985 |
|
JP |
|
05098203 |
|
Apr 1993 |
|
JP |
|
WO9623844 |
|
Aug 1996 |
|
WO |
|
WO97/35933 |
|
Oct 1997 |
|
WO |
|
WO 01/90262 |
|
Nov 2001 |
|
WO |
|
WO 01/090262 |
|
Nov 2001 |
|
WO |
|
Other References
English Machine translation of JP 05-098203. cited by examiner
.
Keeling, Phys. Technol., 12(5), 195-303 (1981), no month available.
cited by other .
Kuhn et al., Scientific American, Apr. 1979, 162-178. cited by
other.
|
Primary Examiner: Koslow; C. Melissa
Assistant Examiner: Faison-Gee; Veronica
Attorney, Agent or Firm: Leydig, Voit & Mayer, Ltd
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. provisional patent
application No. 60/446,543, filed Feb. 12, 2003, the disclosure of
which is incorporated by reference.
Claims
What is claimed is:
1. A jet ink composition comprising methyl ethyl ketone and/or
acetone as solvent, a rosin ester resin, a vinyl resin, and a
colorant, wherein said jet ink composition has (1) a viscosity from
about 1.6 to about 10.0 centipoises at 25.degree. C.; (2) an
electrical resistivity from about 50 to about 2000 ohm-cm; and (3)
a sonic velocity from about 1100 to about 1700 meters/second.
2. A jet ink composition comprising methyl ethyl ketone and/or
acetone as solvent, a rosin ester resin, a vinyl resin, and a
colorant, wherein the jet ink composition is free or substantially
free of a cellulose nitrate resin and slow evaporating solvents
wherein the slow evaporating solvents have an evaporation rate of
less than about 0.5 where n-butyl acetate has an evaporation rate
of 1.0, wherein said jet ink composition has (1) a viscosity from
about 1.6 to about 10.0 centipoises at 25.degree. C.; (2) an
electrical resistivity from about 50 to about 2000 ohm-cm; and (3)
a sonic velocity from about 1100 to about 1700 meters/second.
3. The jet ink composition of claim 1, wherein the rosin ester
resin is a hydrogenated rosin ester resin.
4. The jet ink composition of claim 3, wherein tile hydrogenated
rosin ester rosin is a glycerol modified hydrogenated rosin ester
resin.
5. The jet ink composition of claim 1, wherein the colorant is a
dye, pigment, lake, or a combination thereof.
6. The jet ink composition of claim 5, wherein the colorant is a
dye.
7. The jet ink composition of claim 1, further comprising a
plasticizer.
8. The jet ink composition of claim 1, further comprising a wetting
agent.
9. The jet ink composition of claim 1, further comprising a
defoamer.
10. The jet ink composition of claim 1, wherein the solvent is
present in an amount of from about 70% to about 90% by weight of
the composition, the rosin eater resin is present in an amount of
from about 1% to about 20% by weight of the composition, the vinyl
rosin is present in an amount of from about 2% to about 10% by
weight of the composition, and the colorant is present in an amount
of from about 2% to about 15% by weight of the composition.
11. The jet ink composition of claim 10, further comprising a
wetting agent in an amount of from about 0.1% to about 1% by weight
at the composition.
12. The jet ink composition of claim 10, further comprising a
plasticizer in an amount of from about 0.1% to 2% by weight of the
composition.
13. The jet ink composition of claim 10, further comprising a
detained in an amount of from 0.5% to about 1.5% by weight of the
composition.
14. A method for printing messages having adhesion on a low surface
energy substrate comprising projecting a stream of droplets of the
jet ink composition of claim 1, to the substrate, controlling the
direction of the stream so that the droplets are caused to form the
desired printed messages, and allowing the messages to dry.
15. The method of claim 14, wherein the low surface energy
substrate is a plastic.
16. The method of claim 15, wherein the plastic is a polyolefin or
a halogenated polyolefin.
17. The method of claim 16, wherein the polyolefin is
polypropylene.
18. The method of claim 17, wherein the polypropylene is mono- or
bi-axially oriented polypropylene.
19. The method of claim 14, wherein the low surface energy
substrate is an oil-contaminated metal.
20. A jet ink composition comprising methyl ethyl ketone and/or
acetone as solvent, a rosin ester resin, a vinyl resin, a
cellulosic resin, and a colorant.
21. The jet ink composition of claim 20, which is also free of
cellulose nitrate and free or substantially free of slow
evaporating solvents, wherein the stow evaporating solvents have an
evaporation rate of less than about 0.5 where n-butyl acetate has
an evaporation rate of 1.0.
22. A method for printing messages having adhesion on a low surface
energy substrate comprising projecting a steam of droplets of the
jet ink composition of claim 20, to the substrate, controlling the
direction of the stream so that the droplets are caused to form the
desired printed messages, and allowing the messages to dry.
Description
FIELD OF THE INVENTION
This invention pertains to ink jet ink compositions suitable for
printing messages having improved adhesion and scratch resistance.
The invention is especially advantageous for printing messages on
low surface energy substrates in general, and in particular, low
surface energy plastic substrates and oil-contaminated metal
substrates. The invention also pertains to a method for printing
such messages with improved adhesion and scratch resistance.
BACKGROUND OF THE INVENTION
Ink jet printing is a well-known technique by which printing is
accomplished without contact between the printing device and the
substrate on which the printed characters are deposited. Briefly
described, ink jet printing involves the technique of projecting a
stream of ink droplets to a surface and controlling the direction
of the stream so that the droplets are caused to form the desired
printed image on that surface. This technique of noncontact
printing is particularly well suited for application of characters
onto substrates such as glass, metal, or plastic containers and
packages.
Reviews of various aspects of ink jet printing can be found in
these publications: Kuhn et al., Scientific American, April, 1979,
162-178; and Keeling, Phys. Technol., 12(5), 196-303 (1981).
Various ink jet apparatuses are described in the following U.S.
Pat. Nos. 3,060,429, 3,298,030, 3,373,437, 3,416,153, and
3,673,601.
In general, an ink jet ink composition must meet certain
requirements to be useful in ink jet printing operations. These
requirements relate to viscosity, resistivity, solubility,
compatibility of components and wettability of the substrate.
Further, the ink must be quick-drying and smear resistant, resist
abrasion, and be capable of passing through the ink jet nozzle
without clogging, and permit rapid cleanup of the machine
components with minimum effort. In addition, the printed messages
must have sufficient adhesion to the substrates.
Plastic substrates, particularly polyolefins, are often used in
packaging. For example, oriented polypropylene (OPP) films are
widely used as packaging materials such as the over-wraps for
cigarette packages and cartons because of their ability to heat
seal and provide good barrier properties in maintaining freshness
and moisture content of the packaged goods. These and other low
surface energy substrates present certain problems with respect to
the quality and robustness of the printed message. The messages are
sometimes rubbed off or scratched off during normal handling even
with relatively moderate force if the adhesion of the message to
the substrate is poor. In order to alleviate this problem, the
plastic substrates are sometimes provided with a surface
pretreatment such as oxidation, carona treatment or plasma
treatment, or a coating of a primer. However, such pretreatments
undesirably add to the cost of the package manufacturing
process.
Further, OPP films often contain slip additives to provide adequate
seal release or coefficient of friction. These additives are
predominantly migratory fatty acid amides, which bloom to the film
surface and provide the slip property. These additives are believed
to be contributing factors in the degradation of ink adhesion over
time as well as adhesion variation due to the age difference of the
films. The presence of such additives makes the ink adhesion on low
surface energy films even more challenging.
Some attempts have been made to provide ink compositions for
improving the adhesion of the printed message to low surface energy
plastic substrates, for example, by the use of certain acrylamides
or chlorinated polypropylene resin; see, for example, U.S. Pat.
Nos. 5,430,093 and 5,500,251. However, other approaches are
desirable.
The foregoing indicates that there is a need for a jet ink
composition that is suitable for printing on plastic surfaces,
particularly low energy surfaces such as polyolefin surfaces,
messages that have abrasion or scratch resistance in general, and
in particular, messages that have fingernail scratch or finger rub
resistance.
The invention provides such a composition. The advantages of the
invention, as well as additional inventive features, will be
apparent from the description of the invention provided herein.
BRIEF SUMMARY OF THE INVENTION
The foregoing needs have been fulfilled to a great extent by the
present invention which provides a jet ink composition suitable for
printing messages on substrates, such as plastics, that have
abrasion resistance and scratch resistance. The jet ink composition
comprises one or more organic solvents, a rosin resin, and a
colorant, and optionally a co-binder resin, e.g., a vinyl resin.
Preferably, the jet ink composition is free or substantially free
of a cellulose nitrate resin and/or a slow evaporating solvent.
The present invention further provides a method for printing
abrasion or scratch resistant messages on a substrate comprising
projecting a stream of droplets of the jet ink composition to the
substrate, controlling the direction of the stream so that the
droplets are caused to form the desired printed messages, and
allowing the messages to dry.
The foregoing advantages of the present invention, as well as
additional inventive features, will be apparent from the
description of the embodiments of the invention provided
herein.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a jet ink composition suitable for
printing on substrates, such as low surface energy plastics
messages, having abrasion or scratch resistance, the composition
comprising one or more organic solvents, a colorant, and a rosin
resin. The ink composition may further include one or more
ingredients such as co-binder resins, plasticizers, wetting agents,
defoamers, and conductivity agents.
The present invention is predicated on the discovery that jet ink
compositions containing a rosin resin have unique and unexpected
properties. The messages printed on substrates, particularly low
energy substrates such as polyolefins, have excellent adhesion to
the substrates. The messages show improved scratch resistance. A
further advantage of the ink composition of the present invention
is that abrasion resistant messages can be printed on low energy
surfaces even without the use of an adhesion promoter or a surface
treatment. Although not required, it is contemplated that a surface
treatment, or an adhesion promoter, might improve adhesion even
more.
In an embodiment, the present invention provides a jet ink
composition comprising one or more organic solvents, a rosin resin,
a co-binder resin, and a colorant, wherein the jet ink composition
is free or substantially free of a cellulose nitrate resin. In
another embodiment, the present invention provides a jet ink
composition comprising one or more organic solvents, a rosin resin,
a vinyl resin, and a colorant. In a further embodiment, the present
invention provides a jet ink composition comprising one or more
organic solvents, a rosin resin, and a colorant, wherein the jet
ink composition is free or substantially free of a cellulose
nitrate resin and slow evaporating solvents.
The jet ink compositions of the present invention can be used in
continuous or drop on demand printers. When used in continuous ink
jet printing, they have (1) a viscosity from about 1.6 to about
10.0 centipoises at 25.degree. C.; (2) an electrical resistivity
from about 50 to about 2000 ohm-cm; and (3) a sonic velocity from
about 1100 to about 1700 meters/second.
The jet ink compositions of the present invention includes at least
one organic solvent. A mixture of 2, 3, 4, or more organic solvents
can be used. Any suitable solvent can be used, and in a preferred
embodiment, the solvent has sufficient solubility for the rosin
resin and/or the co-binder resin (if a co-binder resin is used),
and in a more preferred embodiment, the solvent has sufficient
solubility for the rosin resin as well as the co-binder resin. The
organic solvent also preferably has sufficient volatility, or
evaporation rate, to provide suitable, e.g., short, dry times of
the printed messages. Examples of organic solvents include
alcohols, ketones, esters, ethers, amides, and combinations
thereof, and preferably ketones, more preferably lower ketones. A
particular example of an organic solvent is methyl ethyl ketone. If
water is present, it is preferable to keep the water content low,
for example, below 5%, more preferably below 2%, and more
preferably below 1%, by weight of the solvent mixture.
The organic solvent, or a mixture of solvents, can be present in
any suitable amount, for example, in an amount of up to about 90%
by weight of the jet ink composition. In an embodiment, the organic
solvent, or a mixture of solvents, can be present in an amount of
from about 30% by weight to about 90% by weight, preferably in an
amount of from about 50% to about 80% by weight, of the jet ink
composition. In another embodiment, the organic solvent, or a
mixture of solvents, can be present in an amount of from about 70%
to about 90% by weight, and preferably in an amount of about 75% to
85% by weight, of the jet ink composition.
The jet ink composition, according to certain embodiments of the
invention, are free or substantially free of slow evaporating
solvents, for example, solvents having an evaporation rate of about
0.5 or less, preferably about 0.3 or less, and more preferably
about 0.2 or less, relative to n-butyl acetate which has an
evaporation rate of 1.0. See, for example, U.S. Pat. No. 6,444,019,
column 5, lines 2-26. If a slow evaporating solvent is present, it
is preferably present in a small quantity, for example, about 5% by
weight or less, more preferably about 3% by weight or less, and
even more preferably about 1% by weight or less, of the jet ink
composition.
The jet ink composition of the present invention comprises a rosin
resin. Any suitable rosin resin can be used. The rosin resin can be
a natural resin or a modified resin. Modified rosin resins include,
for example, stabilized rosin resins, polymerized rosin resins, and
esterified rosin resins. Esterification can be carried out using
monovalent alcohols such as alcohols such as methanol, ethanol,
propanol and the like, and polyvalent alcohols such as ethylene
glycol, propylene glycol, glycerol, pentaerythritol, and the like.
The rosin resin can also be modified by addition reactions such as
by addition of a maleic anhydride or by hydrogenation or
dehydrogenation to render the rosin resin more stable, e.g., to
oxidation. In a preferred embodiment, the rosin resin is a glycerol
modified hydrogenated rosin ester. In an embodiment, the rosin
resin has a low acid number, for example about 20 or less, e.g.,
about 10 or less, preferably about 8 or less. An example of a
glycerol modified hydrogenated rosin ester is STAYBELITE.RTM. Ester
10, available from Hercules Inc., which has an acid number of
8.
The rosin resin can be present in any suitable amount, for example,
in certain embodiments, in an amount of from about 20% by weight to
about 40% by weight, and preferably about 25% by weight to about
35% by weight, of the jet ink composition, and in certain other
embodiments, in an amount of from about 5% by weight to about 20%
by weight, and preferably from about 7% by weight to about 15% by
weight, of the jet ink composition. The amount of rosin resin can
also range from about 1 to about 5% in some embodiments, e.g.,
where a pigment is present.
Without wishing to be bound by any theory or mechanism, it is
believed that the rosin resin, when present in the printed message,
acts as a solid solvent for the slip additive that blooms to the
surface of the substrate. As the slip additive is soaked up (or
dissolved) by the rosin resin in the printed image, the additive
does not reside at the interface between the substrate and the
printed message. This soaking up or dissolution of the additive
prevents the deterioration of the adhesion between the printed
message and the substrate. It is believed that this phenomenon may
be responsible for the improved adhesion. The ink jet ink
composition also is able to penetrate certain contaminants found on
substrates, such as oily contaminants found on parts of metal cans,
e.g., lids, to provide good adhesion to the substrates.
The jet ink composition of the present invention, in embodiments,
may include one or more co-binder resins. Any suitable co-binder
resin can be used. Examples of co-binder resins include vinyl
resins, acrylic resins, styrene-acrylic resins, silicone resins,
polyesters, polyamides, polyvinylpyrrolidone, polyurethane resins,
epoxy resins, alkyd resins, hydrocarbon resins, nitrocellulose (or
cellulose nitrate), cellulosic resins, cellulose acetate, ketone
resins, and aldehyde resins. In certain embodiments, high molecular
weight co-binder resins are preferred, for example, co-binder
resins having a molecular weight of about 10,000 or more. A
particular example of a co-binder resin is BAKELITE.TM. VMCH resin
(Union Carbide), which is a 86:13:1 terpolymer of vinyl chloride,
vinyl acetate, and maleic acid having a number average molecular
weight of about 21,000.
The co-binder resin can be present in any suitable amount,
preferably in an amount less than the rosin resin. For example, the
co-binder resin can be present in an amount of from about 1% by
weight to about 20% by weight, preferably from about 2% by weight
to about 10% by weight, and more preferably from about 3% by weight
to about 5% by weight, of the jet ink composition.
Jet ink compositions, in accordance with some embodiments of the
invention, are free or substantially free of a nitrocellulose
resin. If present, the nitrocellulose resin is present in a small
quantity, for example, in an amount of about 5% by weight or less,
more preferably about 3% by weight or less, and even more
preferably about 1% by weight or less.
The jet ink composition of the present invention includes a
colorant, which can be a dye, pigment, or lake, a combination
thereof. Preferably, the colorant is a dye. Any dye that may be
dissolved in the ink composition may be used in the instant
invention. Examples of dyes suitable for use in the ink composition
of the present invention include, but are not limited to, the
yellow dyes such as C.I. Solvent Yellow 19 (C.I. 13900A), C.I.
Solvent Yellow 21 (C.I. 18690), C.I. Solvent Yellow 61, C.I.
Solvent Yellow 80, and the like, the orange dyes such as C.I.
Solvent Orange 1 (C.I. 11920), C.I. Orange 37, C.I. Orange 40, and
the like, red dyes such as C.I. Solvent Red 8, C.I. Solvent Red 81,
C.I. Solvent Red 82, C.I. Solvent Red 84, C.I. Solvent Red 100, and
the like, violet dyes such as C.I. Solvent Violet 8, C.I. Solvent
Violet 21, and the like, blue dyes such as C.I. Solvent Blue 2,
C.I. Solvent Blue 11, C.I. Solvent Blue 25, C.I. Solvent Blue 36,
C.I. Solvent Blue 55, and the like, green dyes such as C.I. Solvent
Green 3 and the like, brown dyes such as C.I. Solvent Brown, and
the like, black dyes such as C.I. Solvent Black 3, C.I. Solvent
Black 5, C.I. Solvent Black 7, C.I. Solvent Black 22, C.I. Solvent
Black 27, C.I. Solvent Black 29, and the like. A particular example
of a dye is C.I. Solvent Black 29, which is commercially available
as Valifast Black 3810 (Orient Chemical) or Orasol Black RLI
(Ciba).
In certain embodiments of this invention, a pigment may be
preferred; for example, if the intended substrates are dark
colored, an opaque pigment will provide better contrast. Both
organic and inorganic pigments are suitable. Examples of suitable
opaque inorganic pigments include titanium dioxide-anatase and
rutile, Bismuth Vanadate, zinc oxide, zinc sulfide, and lithopone.
Examples of suitable opaque organic pigments include Pigment Yellow
139, Pigment Orange 16, Pigment Orange 34, Pigment Orange 61,
Pigment Orange 62, Pigment Orange 64, Pigment Red 254, Pigment Red
255, Pigment Brown 5, and the like. Another example of organic
pigments is carbon black. Carbon black includes channel black,
furnace black, and lamp black. Examples of other suitable organic
and inorganic pigments include Metallized Azo Reds such as Red 49:1
(Barium salt), Red 49:2 (Calcium salt), Red 63:1 (Calcium salt),
Toluidine Reds, Naphthol Reds, Pyrazalones, Rhodamines,
Quinacridones such as Red B, Red Y, Magenta B, Magenta and Violet,
Phthalocyanine Blues, Phthalocyanine Greens, Carbazole Yellow,
Monoarylide Yellow, Diarylide Yellow, Chrome Yellow, Red Lake C,
Lithol Reds such as calcium and barium salts, Lithol Rubine, Bon
Maroon, Perylene pigments, Red 2B pigments including the calcium,
barium and magnesium salts, Chrome yellow, Chrome Orange, Molybdate
Orange, Lead Chromes, Lead Silicochromates, Zinc Chromes, barium
chromate, strontium chromate, titanium nickel yellow, Liminites,
Haematite, Magnetite, Micaceous Oxides of Iron, Siderite, Iron
Pyrites, Ferrite Yellow, Red Oxide, Prussian Blue, Orange 36,
Diarylide Orange, Dianisidine Orange, Tolyl Orange, and
Dinitraniline Orange. Other suitable examples of pigments include
lakes, for instance, lakes formed from acid dyes and alkali or
alkaline earth metals.
The colorant can be present in the ink composition in any amount
required to produce the desired contrast and readability. The
colorant is preferably present in an amount of from about 1% to
about 18% by weight of the jet ink composition and more preferably
in the range of about 2% to about 15% by weight of the jet ink
composition.
The jet ink composition in accordance with embodiments of the
invention may also include a plasticizer. It is believed that the
plasticizer improves the flexibility of the film that forms when
the ink dries on the substrate. The improved flexibility may
contribute to a certain extent to an improvement in abrasion
resistance. Any suitable plasticizer known in the industry can be
used. See, e.g., U.S. Pat. No. 5,594,044 which discloses at column
6, line 36, to column 7, line 6, plasticizers suitable for use in
ink jet compositions, the disclosure of which is incorporated
herein by reference. A preferred plasticizer for use in the ink
composition of the present invention is SANTICIZER.TM. 160 which is
butyl benzyl o-phthalate and available from Monsanto Co.
The plasticizer can be present in any suitable amount. For example,
the plasticizer can be present in the jet ink composition in an
amount of up to about 5% by weight of the ink composition,
preferably in an amount of from about 0.5% by weight to about 3% by
weight, and more preferably in an amount of from about 0.5% to
about 2% by weight of the ink composition.
The jet ink composition in accordance with some embodiments of the
invention may further include a wetting agent, for example, to
control the droplet size of the ink. Any suitable wetting agent may
be used. An example of a wetting agent is a surfactant. The
surfactant may be anionic, cationic, nonionic, or amphoteric.
SILWET.TM. L-7622, available from Witco Corp., OSI Specialties
Group, Tarrytown, N.Y., is a silicone based wetting agent and is an
example of a preferred wetting agent. For additional wetting
agents, see, e.g., U.S. Pat. No. 5,594,044, column 5, lines 43-64,
the disclosure of which is incorporated herein by reference.
The wetting agent may be present in the jet ink composition in an
amount of up to about 1% by weight, preferably in an amount of
about 0.1% to about 1% by weight of the jet ink composition.
The jet ink composition in accordance with some embodiments of the
invention may include a defoamer. The defoamer reduces the foaming
tendency of the jet ink composition. An example of a suitable
defoamer is BYK.TM. 065 from BYK-Chemie USA. The defoamer can be
present in any suitable amount of, e.g., up to about 1% by weight
of the jet ink composition.
The jet ink composition may also contain other additives generally
known in the ink jet ink printing art, e.g., for adjusting the
viscosity, electrical resistivity, and the speed of evaporation.
One or more humectants can be present.
The jet ink compositions may also contain one or more conductivity
agents. If present, they would typically be present in an amount of
up to about 2.0% by weight of the ink composition. Examples of
suitable conductivity agents include lithium
trifluoromethanesulfonate, tetraethylammonium p-toluenesulfonate,
tetrabutylphosphonium bromide, tetrapropylammonium bromide,
tetrabutylammonium chloride, tetrabutylammonium nitrate,
tetrabutylammonium hexafluorophosphate. Sufficient conductivity may
be offered by some of the dyes (e.g., soluble dyes) in the presence
of the solvent used in the ink and a conductivity agent may not be
necessary. If a pigment is used, then a conductivity agent may be
needed.
The present invention provides embodiments of the jet ink
composition wherein the one or more organic solvents are present in
an amount of from about 50% to about 80% by weight of the
composition, the rosin resin is present in an amount of from about
20% to about 40% by weight of the composition, and the colorant is
present in an amount of from about 5% to about 10% by weight of the
composition. The jet ink composition may further comprise a wetting
agent in an amount of from about 0.1% to about 1% by weight of the
composition.
The present invention also provides embodiments wherein the one or
more organic solvents are present in an amount of from about 70% to
about 90% by weight of the composition, the rosin resin is present
in an amount of from about 1% to about 20% by weight of the
composition, the co-binder resin is present in an amount of from
about 2% to about 10% by weight, preferably from about 2% to about
6% by weight of the composition, and the colorant is present in an
amount of from about 2% to about 15% by weight of the composition.
The jet ink composition may further comprise a wetting agent in an
amount of from about 0.1% to about 1% by weight of the composition,
a plasticizer in an amount of from about 0.1% to 2% by weight of
the composition, and/or a defoamer in an amount of from 0.5% to
about 1.5% by weight of the composition.
The present invention further provides a method for printing
messages having adhesion on a low surface energy substrate
comprising projecting a stream of droplets of any of the jet ink
composition described above to the substrate, controlling the
direction of the stream so that the droplets are caused to form the
desired printed messages, and allowing the messages to dry. In
accordance with the present invention, any suitable substrate
having low surface energy can be printed on. An advantage of the
ink composition of the present invention is that substrates that
include a blooming additive such as a fatty amide can be printed
with messages that have improved scratch and adhesion
resistance.
Examples of suitable substrates include plastics and oil or
lubricant coated or contaminated metals. Examples of plastics
include polyolefins such as polyethylene and polypropylene,
preferably polypropylene; and halogenated polyolefins, e.g.,
polyvinyl chloride (PVC). The plastics can be oriented or
non-oriented. If oriented, they can be monoaxially oriented,
biaxially oriented, or a combination thereof, preferably biaxially
oriented. A particular example of a suitable substrate is biaxially
oriented polypropylene (BOPP) such as the over-wrap films used on
most cigarette packages and cartons. It is contemplated that
substrates such as homopolymers and copolymers of haloolefins and
olefins, e.g., polyvinylidene fluoride, PTFE,
polychlorotrifluoroethylene, copolymers of vinyl chloride and
vinylidene chloride, may also be suitable for printing with the jet
ink composition of the present invention. In embodiments, the
substrates have a surface energy of about 40 dynes/cm or less.
The following examples further illustrate the invention but, of
course, should not be construed as in any way limiting its
scope.
EXAMPLES
These Examples illustrate jet ink compositions prepared in
accordance with certain embodiments of the present invention (Table
1). These Examples also illustrate some of the properties of the
jet ink composition of the present invention (Tables 2-5). The jet
ink compositions of Examples 1-4 are printed on samples of BOPP
films and the finger nail scratch resistance of the printed codes
are determined as a function of time after printing, by scratching
10 times with light pressure, and the degree of code removal is
recorded. Comparative Examples 1-4 are commercial jet ink
compositions. The results from finger nail scratch resistance tests
are set forth in Tables 2-4. The BOPP samples may have aged
differently as the time of arrival in applicants' laboratory
differed. Thus, sample No. 1 arrived the earliest, sample Nos. 2
and 4 arrived later, and sample Nos. 3, 5, and 6 arrived
subsequently. Scratch resistance rating: 1--no change; 2--slight
removal; 3--partial removal; 4--mostly removed; and 5--complete
removal.
Finger rub resistance of a code on a difficult to print can lid is
tested and the number of hard finger rubs to remove the codes is
set forth in Table 5.
TABLE-US-00001 TABLE 1 Examples of Jet Ink Compositions EXAM- EXAM-
EXAM- EXAM- COMPONENTS PLE 1 PLE 2 PLE 3 PLE 4 Methyl ethyl ketone
83.2 80.7 76.6 61.5 (solvent) STAYBELITE Ester 8.0 10.0 12.0 30.0
10 (rosin ester) BAKELITE VMCH 3.3 3.3 5.0 (vinyl resin) SANTICIZER
160 1.0 1.0 (plasticizer) ORASOL BLACK 4.0 4.5 5.0 8.0 RLI (dye)
SIL WET L-7622 0.5 0.5 0.5 0.5 (wetting agent) BYK 065 (defoamer)
0.9 Total 100% 100% 100% 100%
TABLE-US-00002 TABLE 2 Finger nail scratch resistance 72 hrs after
printing Sample Ex. Ex. Ex. Ex. Comp. Comp. Comp. Comp. Nos. 1 2 3
4 Ex. 1 Ex. 2 Ex. 3 Ex. 4 1 2 1 1 2 4 5 5 5 2 1 1 1 1 4 5 5 5 3 2 2
1 2 3 4 5 4 4 1 1 1 2 4 4 5 4 5 1 1 1 1 4 4 5 5 6 1 1 1 1 3 4 5
5
TABLE-US-00003 TABLE 3 Finger nail scratch resistance 24 hrs after
printing Sample Ex. Ex. Ex. Ex. Comp. Comp. Comp. Comp. Nos. 1 2 3
4 Ex. 1 Ex. 2 Ex. 3 Ex. 4 1 2 1 1 2 3 4 5 4 2 1 1 1 1 3 4 4 3 3 1 1
1 2 3 3 5 3 4 1 1 1 2 3 4 5 4 5 1 1 1 2 3 3 5 4 6 1 1 1 1 3 3 5
4
TABLE-US-00004 TABLE 4 Finger nail scratch resistance 1 hr after
printing Sample Ex. Ex. Ex. Ex. Comp. Comp. Comp. Comp. Nos. 1 2 3
4 Ex. 1 Ex. 2 Ex. 3 Ex. 4 1 2 2 1 1 3 3 5 4 2 1 1 1 1 3 2 4 3 3 2 1
1 2 2 2 4 3 4 1 1 1 2 3 2 5 3 5 1 1 1 2 2 3 5 3 6 1 1 1 1 3 2 5
3
TABLE-US-00005 TABLE 5 Finger rub resistance of code on can lid 1
hr after printing Example 1 Com. Ex. 1 Com. Ex. 2 Com. Ex. 4 Can
lid 10+ 2-3 3-4 4-5
The foregoing shows that the jet ink compositions of the present
invention have excellent adhesion (finger nail scratch resistance
and finger rub resistance) to low surface energy substrates. While
the jet ink compositions of the present invention are especially
advantageous for use with low surface energy substrates, the
inventive jet ink compositions would also provide improved adhesion
and scratch resistance on high surface energy substrates.
All references, including publications, patent applications, and
patents, cited herein are hereby incorporated by reference to the
same extent as if each reference were individually and specifically
indicated to be incorporated by reference and were set forth in its
entirety herein.
The use of the terms "a" and "an" and "the" and similar referents
in the context of describing the invention (especially in the
context of the following claims) are to be construed to cover both
the singular and the plural, unless otherwise indicated herein or
clearly contradicted by context. The terms "comprising," "having,"
"including," and "containing" are to be construed as open-ended
terms (i.e., meaning "including, but not limited to,") unless
otherwise noted. Recitation of ranges of values herein are merely
intended to serve as a shorthand method of referring individually
to each separate value falling within the range, unless otherwise
indicated herein, and each separate value is incorporated into the
specification as if it were individually recited herein. All
methods described herein can be performed in any suitable order
unless otherwise indicated herein or otherwise clearly contradicted
by context. The use of any and all examples, or exemplary language
(e.g., "such as") provided herein, is intended merely to better
illuminate the invention and does not pose a limitation on the
scope of the invention unless otherwise claimed. No language in the
specification should be construed as indicating any non-claimed
element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein,
including the best mode known to the inventors for carrying out the
invention. Variations of those preferred embodiments may become
apparent to those of ordinary skill in the art upon reading the
foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all
modifications and equivalents of the subject matter recited in the
claims appended hereto as permitted by applicable law. Moreover,
any combination of the above-described elements in all possible
variations thereof is encompassed by the invention unless otherwise
indicated herein or otherwise clearly contradicted by context.
* * * * *